Radioactive compositions have a range of diagnostic and therapeutic applications. However, the half-life of radiopharmaceuticals is typically on the order of hours, and it is therefore not possible to retain stocks of such compounds within hospitals, clinics and/or research laboratories. Rather, it is necessary to synthesise and purify radiopharmaceuticals on-demand, for example within a hospital or clinical laboratory. Purification is often achieved via chromatographic techniques, such as high-performance liquid chromatography (HPLC), which perform temporal and spatial separation of the desired product from attendant impurities and by-products.
Such methods of purification carry an associated risk of the product including impurities, for example if collection is commenced too early, or concluded too late. It is undesirable, and potentially highly detrimental, for impurities or by-products of radiopharmaceutical synthesis to be injected into the patient or subject.
The operator of the synthesis and purification apparatus may therefore adopt a conservative approach, for example collecting only a portion of the desired product by commencing collection later than necessary and/or halting collection earlier than necessary. This results in a reduced volume of the desired radiopharmaceutical product, with an associated risk that an insufficient activity of the desired product will be collected.